function s = sigmasqonxi

s.sq0 = @sq0;
s.sq1 = @sq1;
s.sqonxi = @sqonxi;

function y = Ak(k,T)
y = sqrt(2/T)/(1+((k-1)*pi/T)^2);

function y = Bk(k,T)
y = (k-1)*pi/T;


function y = sq0(t,T)   % checked
y = 3/2*(T-t)+1/4*exp(-2*T)-1/4*exp(-2*t);

function y = sq1(t,T)   % checked
y = 2*(1/sqrt(T)*(T-t+exp(-T)-exp(-t)));

function y = sqonxi(k,t,T) % checked
y = 2*(Ak(k,T)*(-1/Bk(k,T)*sin(Bk(k,T)*t)+exp(-T)-exp(-t)-(-1)^(k-1)+cos(Bk(k,T)*t)));



















